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site should be greater than six square root of the
number of all the grid sites. We denote the num-
ber of all the grid sites by
N
, and the minimal
number of neighbors should be greater than or
equal to
N
Besides, the average utilization, the maximum
utilization and the minimum utilization of resource
i
of site
s
are defined by
U_AVG
i
(
s
),
U_MAX
i
(
s
)
and
U_MIN
i
(
s
) respectively. Therefore, the
RL
of
site
s
is defined as
6
. Therefore, each grid site maintains
at least
6
neighbors to ensure the network
connectivity. In addition, in order to improve the
load balancing, SALB estimates the remaining
resources capability of each neighbor site and
selects the neighbors with more remaining capa-
bilities for migrating jobs. Suppose that a grid site
has
m
kinds of resources, and each resource's
remaining capability of site
s
is denoted by
RC
i
(
s
),
where
i
= 1 …
m
. The weight of each resource is
denoted by
W
i
(
s
). Assume that
DRC
(
l
,
r
) is the
difference of remaining capability between the
local site
l
and the remote site
r
. Then,
U U AVG s
U MAX s
−
_
( )
m
∑
RL s
=
W s
i
i
( )
( )
( )
i
_
( )
−
U MIN s
_
=
i
i
i
i
(2)
while the
AL
of site
s
is defined as
m
∑
1
AL s
=
W s U s
i
( )
( )
( )
(3)
i
i
=
Moreover, SALB predefines the high threshold
of
RL
by
RL_H
, the low threshold of
RL
by
RL_L
,
the high threshold of
AL
by
AL_H
, and the low
threshold of
AL
by
AL_L
. The status of different
combinations of
RL
and
AL
are described as fol-
lows: When
RL
is greater than or equal to
RL_H
,
the status is set to be “High”. When
RL
is less than
RL_H
and is greater than
RL_L
, the status is set
to be “Moderate”. When
RL
is less than or equal
to
RL_L
, the status is set to be “Low”. When
AL
is greater than or equal to
AL_H
, the status is set
to be “High”. When
AL
is less than
AL_H
and is
greater than
AL_L
, the status is set to be “Moder-
ate”. When
AL
is less than or equal to
AL_L
, the
status is set to be “Low”. The statuses of different
combinations of
RL
and
AL
are shown in table 1.
According to the statuses of
RL
and
AL
, we
classify the status of local sites to be “Sendable”
RC l
RCi rii
( )
( )
m
∑
1
DRC l r
( , )
=
W l
( )
i
(1)
i
i
=
When a gird site joins the P2P Grid system, it
randomly selects 2
6
sites as the candidates of
neighbors and picks the first
6
sites with the
smaller
DRC
as its neighbors. Thus, these neigh-
bors have more remaining resources capability
for load balancing. To avoid the out-of-date in-
formation, we also set a time interval
t
for each
grid site to re-select neighbor sites periodicity. In
addition, SALB estimates the relative loading
(
RL
) and the absolute loading (
AL
) of grid sites
to determine whether the local site is sendable
and which neighbor sites are receivable. We define
the utilization of resource
i
in site
s
by
U
i
(
s
).
Table 1. States of RL and AL
RL
status
AL
status
RL
≧
RL_H
High
AL
≧
AL_H
High
RL_H > RL
>
RL_L
Moderate
AL_H > AL
>
AL_L
Moderate
RL
≦
RL_L
Low
AL
≦
AL_L
Low
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